Image processing apparatus, image processing method, image processing program, and image pickup apparatus acquiring a focusing distance from a plurality of images

• US 8,988,592 B2
• Filed: 04/15/2013
• Issued: 03/24/2015
• Est. Priority Date: 05/17/2012
• Status: Expired due to Fees

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Takahashi, Takahiro
• Primary Examiner(s): VILLECCO, JOHN M
• Application Number:
  US13/862,880
• Publication Number:
  US 20130308005A1
• Time in Patent Office: 708 Days
• Field of Search: 348/208.12, 348/349, 348/352, 382/106, 382/107, 382/255
• US Class Current: 348/349
• CPC Class Codes: G06F 18/22 Matching criteria, e.g. proximity measures
• CPC Class Codes: G06T 5/73 Deblurring; Sharpening
• CPC Class Codes: G06T 7/30 Determination of transform parameters for the alignment of images, i.e. image registration
• CPC Class Codes: G06T 7/60 Analysis of geometric attributes
• CPC Class Codes: H04N 23/676 Bracketing for image capture at varying focusing conditions
• CPC Class Codes: H04N 23/959 by adjusting depth of field during image capture, e.g. maximising or setting range based on scene characteristics

Abstract

An image processing apparatus that acquires a focusing distance from a plurality of images each having different degrees of blur, includes: a misalignment detection unit that detects misalignment among the plurality of images; a distance information acquisition unit that acquires, based on the plurality of images, distance information, which is information to indicate a focusing distance in an area of the images; and a reliability information acquisition unit that creates, based on the detected misalignment, reliability information, which is information to indicate reliability of the focusing distance acquired for each area, wherein the distance information acquisition unit changes the acquired distance information based on the reliability information.

Claims

1. An image processing apparatus that acquires a focusing distance from a plurality of images each having different degrees of blur, comprising:

a misalignment detection unit that detects the amount of misalignment and/or the direction of misalignment among the plurality of images;

a distance information acquisition unit that acquires, based on the plurality of images, distance information, which is information to indicate a focusing distance in an area of the images; and

a reliability information acquisition unit that creates reliability information based on the detected amount of misalignment and/or the detected direction of misalignment, the reliability being information to indicate the reliability of the focusing distance acquired for each area.

2. The image processing apparatus according to claim 1, wherein the distance information acquisition unit changes the acquired distance information based on the reliability information.

3. The image processing apparatus according to claim 2, wherein the distance information acquisition unit determines a correction area where the brightness or the hue of pixels therein is in a predetermined range, and for an area whose the reliability is lower than the predetermined value, uses a focusing distance corresponding to another area belonging to a same correction area to which this area belongs instead of the acquired focusing distance.

4. The image processing apparatus according to claim 1, wherein the reliability information acquisition unit acquires a first difference between misalignment in a target area and average misalignment in surrounding areas of the target area, and sets a lower reliability for the target area compared to a case when the difference between misalignment in a target area and average misalignment in surrounding areas of the target area is a second difference smaller than the first difference.

5. The image processing apparatus according to claim 1, wherein the reliability information acquisition unit creates the reliability information further based on a frequency characteristic of a focused image or a brightness value of pixels therein among the plurality of images photographed.

6. The image processing apparatus according to claim 5, wherein if a spatial frequency of a target area is a first spatial frequency, the reliability information acquisition unit sets a lower reliability for the target area compared with a case when the spatial frequency is a second spatial frequency higher than the first spatial frequency.

7. The image processing apparatus according to claim 1, wherein the reliability information acquisition unit creates the reliability information further based on a difference among the plurality of images photographed.

8. The image processing apparatus according to claim 2, further comprising a depth of field control unit that blurs a focused image among the plurality of images photographed, using the distance information acquired by the distance information acquisition unit.

9. The image processing apparatus according to claim 8, wherein the depth of field control unit decreases a blurring amount for an area having a first reliability compared with a case when the reliability is a second reliability higher than the first reliability.

10. The image processing apparatus according to claim 2, wherein for an area whose the reliability is lower than a predetermined value, the distance information acquisition unit uses a focusing distance corresponding to another area whose the reliability is higher than the predetermined value, instead of the acquired focusing distance.

11. The image processing apparatus according to claim 1, wherein the misalignment detection unit detects the amount of misalignment and the direction of misalignment among the plurality of images.

12. An image pickup apparatus comprising:

an imaging unit; and

the image processing apparatus according to claim 1.

13. An image processing method used by an image processing apparatus that acquires a focusing distance from a plurality of images each having different degrees of blur, the method comprising the steps of:

detecting the amount of misalignment and/or the direction of misalignment among the plurality of images;

acquiring, based on the plurality of images, distance information, which is information to indicate a focusing distance in an area of the images;

creating reliability information based on the detected amount of misalignment and/or the detected direction of misalignment, the reliability information being information to indicate the reliability of the focusing distance acquired for each area.

14. The image processing method according to claim 13, further comprising the step of changing the acquired distance information based on the reliability information.

15. The image processing method according to claim 13, wherein in the detecting step, the amount of misalignment and the direction of misalignment are detected among the plurality of images.

16. A non-transitory storage medium recording an image processing program for causing an image processing apparatus, which acquires a focusing distance from a plurality of images each having different degrees of blur, to execute the steps of:

detecting the amount of misalignment and/or the direction of misalignment among the plurality of images;

acquiring, based on the plurality of images, distance information, which is information to indicate a focusing distance in an area of the images;

creating reliability information based on the detected amount of misalignment and/or the detected direction of misalignment, the reliability information being information to indicate the reliability of the focusing distance acquired for each area.